The speed of an ac motor is directly proportional to the frequency of the alternating current (ac) power supplied to it. Thus, when it is required to alter the speed of an ac motor, the frequency of the ac power supplied to it must be varied.
Typically, such variation is provided by a drive controller which includes three principal components: a power convertor assembly to convert the fixed-frequency ac power supplied to the drive controller into direct current (dc) power; a power invertor to invert the dc power from the convertor into polyphase ac power which is supplied to the motor; and a control assembly which controls the power invertor assembly to vary the frequency of the ac power supplied by the invertor, and hence the speed of the motor.
Drive controllers are continually being developed which offer improvements in the size of the motors which can be controlled, the range of available speeds, the efficiency of the controller, etc.
It is an object of the present invention to provide a novel, modularly constructed AC Drive Controller and modular components therefor.